New Data on the Age of the Kalgyn Ophiolite Massif of the Cherskii Collision Belt (Northeast Asia): Results of U–Th–Pb (SIMS) Geochronological Studies

The Kalgyn massif is a part of the Cherskii collision belt of the Verkhoyansk–Kolyma Fold Area. The Kalgyn massif includes the complex of mantle peridotites, the upper crustal complex of ultramafic cumulates and cumulative gabbro-amphibolites and amphibolites, and the upper crustal complex of metabasalts. The Kalgyn ophiolite massif was formed in both oceanic and suprasubduction geodynamic environments. As followed from previous studies, the rocks of the massif experienced three stages of metamorphism, the age of the earliest (oceanic) stage being 419–430 Ma. Based on these data, the massif was dated to the Early Paleozoic. Here, however, early publications provided data on the more ancient age of ophiolites. This work presents the first results of dating (580.7–614 Ma) magmatic zircons from the gabbro amphibolite of the Kalgyn ophiolite massif, which indicate its Late Riphean age.